Move Mac/Windows specific expected skips from each platform list to the ExpectedSkips class.  Add test_scriptpackages to Mac only list. Add test_unicode_file to Windows only list.
Move Mac/Windows specific expected skips from each platform list
to the ExpectedSkips class.  Add test_scriptpackages to Mac only list.
Add test_unicode_file to Windows only list.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator